Fuel oil supply system



March l0, 1959 R. D. DUY

FUEL OIL SUPPLY SYSTEM Filed Nov. 27, 1957 w51. 52mm Y INVENTOR.

United States Patent O FUEL OIL SUPPLY SYSTEM Robert D. Duy, Summit, N. J. Application November 27, 1957, Serial No. 699,313 5 Claims. (Cl. 15S- 36) The present invention relates to fuel oil supply systems, and more particularly to specific improvements in systems for supplying fuels of high viscosity.

It is now a conventional practice, in many heating in stallations, to utilize economical, high viscosity fuel oils, such as No. 6 or Bunker C fuel oil. At normal temperatures the high viscosity oil is diicult to pump and it is customary to provide means in the fuel supply system for heating the oil to a temperature at which it flows more readily. To this end, it is advantageous to utilize primary heating means, supplied with heat from a fuel burner, to heat the fuel during normal operation of the burner, in combination with electrical heating means, for example, for heating the fuel during start-up or standby operation.

In conventional fuel supply systems, of the type to which the present invention is directed, the high viscosity fuel is contained in a tank provided with a chamber of reduced volume, known as a hot well. A delivery line leads from the hot well, through a pump and a fuel heater, to a suitable burner. It is conventional practice to pump fuel through the delivery line in quantities greater than are required by the burner and a return line is provided, through which the excess fuel is returned to the hot well. Accordingly, during operation of the system, there is a continuous How of fuel through the delivery and return lines and through the heater. The circulating oil is taken from and returned to the hot well so that only a small volume of fuel is required to be heated. Such quantities of fuel as are consumed in the burner are replaced in the circulating system by the flow of lower temperature fuel from the main body of the tank into the hot well.

In the improved system of the invention, the fuel circulating system includes bypass means, operated in accordance with the temperature of the circulating fuel, for causing colder fuel from the supply tank to be introduced into the circulating system whenever the temperature of the circulating fuel reaches a predetermined maximum. Thus, in fuel supply systems incorporating a fuel heater, supplied with heat from the burner, the fuel may tend to reach excessively high temperatures when the demand on the heating installation remains at a low level for an extended period of time. In such cases, little fuel is consumed by the burner and a low volume of low temperature fuel is introduced into the hot well. When this occurs the fuel in the hot well may reach a temperature such that gas is given off and blowback or other undesirable occurrences may be experienced. The system of the present invention avoids any such occurrences byv introducing low temperature fuel into the circulating system at desired times-to prevent the fuel in the hot well from exceeding a predetermined maximum temperature.

More specically, the improved system of the invention incorporates a bypass line connected to the fuel return line and discharging directly into the fuel tank. When the bypass line is open, heated fuel is discharged into the tank, rather than in the hot well, and low tem,

2,876,830 Patented Mar. 10, 197579,

perature fuel from the tank is caused to enter the hot well to lower the average temperature of the fuel therein. For a better understanding of the invention, reference may be made to the accompanying drawing, in which:

Fig. l s a diagrammatic view of a fuel oil supply system embodying the invention; and

Fig. 2 is an enlarged, cross sectional view of a valve, which may be used in the system of Fig. 1.

Referring now to the drawing, the reference numeral 10 designates a supply tank for holding a quantity of high viscosity fuel oil, tank 10 is provided with a hot well 11 in the form of a vertical cylinder having an open bottom 12 spaced a short distance above the bottom of the tank. The top of the hot well projects above the tank 10 and is provided with one or more vent openings 13 of relatively small size, such as one inch in diameter, and a flange 14 surrounds bypass the upper edge of the hot well for receiving a cover 15 serving to close olf the top of the hot well.

A fuel delivery line 16 has a section 17 with its lower end 18 opening in the hot well, about four to six inches above its bottom 12, and leads through a gate valve 19 to a fuel strainer 20. A pump 21 is connected in series in the delivery line 16, on the outlet side of the strainer 20, and has its high pressure on discharge outlet coni nected, through a section 22 of the delivery line, to a fuel heater 23. The heater 23, which may be of conventional design, is supplied with heat from a boiler 24 or other unit heated by means of fuel from the supply system.

The outlet of the fuel heater 23 is connected, through a K delivery line section 25, to an electric preheater 26, which discharges into a delivery line section 27 leading to al strainer 28. The outlet of the strainer 28 is connected to a hinge assembly 29 having a Huid joint 30 therein connected to a metering valve 31 has a pair of outlets 32, 33 leading respectively to a burner 34 and to a second fluid joint 35 in the hinge assembly 29. The burner 34 is connected to the metering valve 31 through a feeder line 36 having therein al gate valve 37 and solenoid valve 38. v

The outlet 33 of the metering valve 31 is connected to the Huid joint 35 by a section 39 of a return line,4

generally designated by the numeral 40. A section 41 of the return line connects the joint 35 with a three-way valve 42 and sections 43, 44 of the return line lead from the valve 42 to the hot well 11, the section 44 having its lower end open in the hot well a few inches below the open end of the delivery line section 17. In accordance n with the invention, a bypass line 45 is connected to the three-way valve 42 and has its discharge end 46 opening in the fuel supply tank 10, outside of the hot well. The three-way valve 42, shown diagrammatically in Fig. 2, is

advantageously a motorized modulating valve capable of" However, as an alternative, and

controlled adjustment. by way of illustration, the valve 42 may be solenoid operated. In the illustrated arrangement, the valve 42 has one limit position, in which the bypass line 45 is closed off, and a second limit position in which the return line sections 43, 44 are closed olf and the return line 40 discharges into the bypass line 45.

An auxiliary bypass line 47 connects the return line sections 41, 43, through a gate valve 48, which is normally closed. Gate valves 49, 50 are also provided in the return line sections 41, 43 respectively, on opposite sides of the three-way valve 42, the valves 49, 50 being normally open. A second auxiliary bypass line 51 connects the return line section 41 with the bypass line 45, through a gate valve 52, which is normally closed. A gate valve 53, which is normally open, in the bypass line 45, The auxiliary bypass lines 47, 51

such as No. 6 or Bunker C oil. The` 31. The metering valve is also provided adjacent the three-way valve 42. and gate valves 48-'50""' and 52, 53 constitute an emergency arrangement for use l livery line section 22, on the outlet side of the fuel pump 21, and discharges through a relief line 55 into the return line section 41. A second relief valve 56 has its inlet connectedto the return line section 41 and its outlet` connected to the auxiliary bypass line 51. The relief valves 54, 56 are normally closed, and open only in response to excessive fuel oil pressures at their respective inlets'.

In accordance with usual practice, the supply system includes a number of automatic control devices. One such control device is a thermostat 57 which is connected to the delivery line section 27 for detecting the temperature of fuel therein. The thermostat 57 controls the electric preheater 26 in such manner that, when the burner 34 is in operation, the preheater 26 is energized when the fuel owing from the preheater is 'below a predetermined temperature. Avisual indication of the temperature of the fuel passing the thermostat may be obtained by means of a conventional thermometer S.

A second thermostat 59, connected in the delivery line. section 22, is provided for standby operation, when the burner 34 is not functioning, and, when the temperature of the fuel at the thrmostat 59 drops below a predetermined level, the preheater 26 and pump 21 are energized. A visual indication of the fuel tempera ture at the thermostat 59 is provided by a thermometer A third thermostat 61 is connected in the delivery line adjacent the metering valve 31 and operates, when the temperature of the fuel at that point drops below a predetermined minimum, to close the solenoid valve 38 in the feeder line 36 leading to the burner 34.

-In accordance with the invention, the three-way valve 42 is controlled by means of a thermostat 62 connected in the delivery line 16, advantageously in the section 22 thereof on the inlet side of the fuel heater 23. When the temperature of the fuel at the thermostat 62 reaches a predetermined Vmaximum an electric circuit is closed to energize the valve 42 and shift the operating member 42a thereof to a position (to the left, as viewed in Fig. 2) in which the return line sections 43, 44 are fully or partially closed otf and the bypass line 45 is connected in circuit with the return line sections 41. Under normal operating conditions, the valve 42 is deenergized so that the bypass line 45 is fully or partially closed off.

To initiate operation of the system, a control switch may be closed to condition the burner 34 for operation. This also energizes the pump 21 and the electric preheater 26, the preheater being under the control of thermostat S7. At the beginning of the start-up period the fuel will be at a lower temperature than is desired for burning and the solenoid valve 33, in the feeder line 37, will be closed by operation of the thermostat 61. With the feeder line 36 closed, the pump 21 causes the fuel to circulate from the hot well 11, through the delivery line 16 and energized electric preheater 26, through.

the metering valve 31 and return line 40, 'back to the hot well. A limited volume of the fuel, as compared to the total supply in the tank 10, is recirculated through the electric preheater 26, until the fuel reaches a temperature such that it is suitable for burning. With Bunker Cl fuel the desired temperature is about 180 F.

When the fuel reaches the desired temperature, the thermostat 61 causes the solenoid valve 38 to open and fuel. is delivered. through the feeder line 36 to the burner 34. In accordance with known practice, the-,metering valve 31 is adjusted so that only a portion of the fuel flowing in the delivery line 16 enters the feeder line 36, the balance of the fuel being directed into the return line 40 and back to the hot well 11. Operation in this manner continues for a period of time, with the circulating fuel being heatedby the electric preheater 26, under the control of the thermostat 57, which shuts off the preheater whenever the fuel temperature exceeds a predetermined value.

After a short period of operation of the burner 34, the `boiler 24 generates steam, a portion of which is directed to the main fuel heater 23. The capacity of the heater 23 is such that it will readily heat the fuel flowing in the delivery line to a temperature above that lat which the thermostat S7 shuts off the electric preheater 26. Accordingly, shortly after the boiler 24 begins to generate steam the electric preheater 26 becomes deenergized and the circulating fuel is heated by the main heater 23.

During periods of heavy demand upon the boiler 24 a relativel;l substantial volume of fuel will be delivered to the burner, and the volume of fuel returning to the hot well through the return line 40 will be considerably less than the volume of fuel withdrawnthrough the delivery line 16. This causes low temperature fuel to ilow into the open bottom 12 of the hot well from the main body of the tank 10, diluting the higher temperature oil in the hot well and maintaining a desired temperature balance in the hot well. However, if the heating demand on the boiler 24 is very low, for an extended period of time, smaller volumes of fuel will be consumed by the burner and correspondingly smaller volurnes of low temperature oil will flow into the hot well from the tank 10. At the same time, the heating capacity of the main heater 23 remains substantially constant, so that the temperature of the circulating oil may increase and may eventually exceed a desired maximum temperature.

In accordance with the invention, when the circulating fuel exceeds a predetermined maximum, the thermostat 62 will cause the valve 42 to be energized in a manner tending to close olf the discharge sections 43, 44 of the f return line and to connect the bypass line 45 in circuit with the return line section 41. Accordingly, at least a portion of the fuel owing in the return line is discharged into the main supply of low temperature oil in the tank 10 and an increased proportion of the fuel drawn out of the hot well 11, through the delivery line 16, must be replaced by the inflow of low temperature oil into the hot well. quickly reduced and when it drops to a predetermined level the thermostat 62 causes the valve 42 to be operated to direct a greater proportion of the returning fuel through the return line sections 43, 44 and into the hot well 11.

When the system is set for standby operation, or where the burner is shut oit for an overnight period, for example, the fuel is maintained at a desired temperature by the electric preheater 26 which, along with the pump 21, is controlled by the thermostat 59. When the fuel temperature at the thermostat 59 drops below a predetermined value the pump 21 and preheater 26 are simultaneously energized, causing fuel to be circulated and heated, until a desired temperature is reached. The pump 21 and preheater 26 will be energized intermittently,

during standby operation or temporarily shut down,

circulating fuel into the tank 10 may be accomplished`l by means of manually operable valves 4S, 52. These valves are normally closed, while valves 49, 50, 53 are normally open. However, by closing the valves 49, .50,

53 and opening one or the other ofthe valves 48, 52 the; fuel may be directed to the hot well 11 or tank 1t),l

as desired. Thus, if the temperature of the circulating fuel exceeds a predetermined value, as indicated by one or both of the thermometers 5S, 60, the valve 52 may be fully or partially opened and the valve 48 fully or partially closed, so thatv at leasta portion. of the returning fuel.:

The temperature of the circulating oil is thus' is directed, through line 51 and bypass line 45, into the tank 10.

The new system is advantageous, in that it provides for heating of the fuel by means supplied with heat from the burner, while preventing the fuel from reaching excessively high temperatures, as during periods where the ow of fuel to the burner is relatively small in proportion to the quantity of fuel owing through the heater. The new system thus minimizes electric power requirements for fuel heating, yet provides the control exibility desired for safety and other purposes.

I claim:

1. In a fuel oil supply system of the type comprising a fuel tank, a hot well in the tank, a fuel circulation system leading from and returning to the hot well, a fuel burner connected to the circulation system and arranged to receive fuel therefrom, fuel heating means in the circulation system supplied with heat from the burner, bypass means connected to the tank and to the circulation system, and thermostatic control means operative when the fuel in the circulation system reaches a predetermined maximum temperature to open the bypass means and eifect a mixing of the heated fuel with fuel from the tank.

2. The fuel oil supply system of claim 1, in which the bypass means, when open, discharges heated fuel from the circulation system into the tank and causes oil from the tank to ow into the hot well.

3. The fuel oil supply system of claim 1, in which the circulation system includes a delivery line leading from the hot well to the burner, the heating means is in the delivery line, andthe thermostatic control means is arranged to detect the temperature of fuel in the delivery line between the hot well and the heating means.

4. The fuel oil supply system of claim 1, in which the circulation system includes a delivery line leading from the hot well to the burner and a return line discharging into the hot well, and the bypass means comprises a bypass line connected to the return line and discharging into the tank and a valve operable by the thermostatic control means for diverting the ow of fuel into the bypass line.

5. A fuel oil supply system according to claim 4, in which the valve means is a three-way valve having one operative condition in which the bypass line is closed off and a second operative condition in which the discharge end of the return line is closed off and the bypass line is open.

References Cited in the le of this patent UNITED STATES PATENTS 1,617,470 Williams Feb. 15, 1927 2,191,688 Thau Feb. 27, 1940 2,599,699 lDilWOrth et al. June 10, 1952 2,747,555 Brunner May 29, 1956 FOREIGN PATENTS 445,720 Great Britain Apr. 17, 1936 

